Unless otherwise indicated herein, approaches described in this section are not prior art to the claims listed below and are not admitted to be prior art by inclusion in this section.
As the LED technology becomes mature, the yields for LED manufacturing has been significantly improved, and the cost decreases accordingly. This makes the products adopting LEDs (e.g., LED flashlights, or LED lamps mounted on vehicles/motorcycles) become much popular in people's daily life.
Among these physical products adopting LEDs, the information signage boards present significant differences. In early days, the appliance of these information signage boards is limited by various factors such as the process yield, the unit cost, and the light emitting efficiency, such that they can only display a single line of information with a single color, besides, sizes of these LEDs adopted are also quite large. A new generation of information signage boards adopting the LEDs is capable of displaying multiple lines of information with various colors and size of the LEDs adopted are tiny.
For the aforesaid new generation of information signage boards adopting the LEDs, a surface thereof for displaying information is provided with a plurality of LED devices 10 arranged in an array. In detail, referring to FIG. 1, each of the LED devices 10 is composed of a substrate 20 and three LED chips 30.
As shown in FIG. 1, an upper surface of the substrate 20 is provided with a first wire-bonding region 21, a second wire-bonding region 22, a third wire-bonding region 23 and a die-bonding region 24, and the three LED chips 30 are a blue chip 31, a green chip 32 and a red chip 33, respectively. The die-bonding region 24 is disposed at the center of the substrate 20, the first wire-bonding region 21 is disposed at one side of the die-bonding region 24, and both the second wire-bonding region 22 and the third wire-bonding region 23 are disposed at the other side of the die-bonding region 24 that is opposite to the first wire-bonding region 21. It shall be noted that, in the circuit design of this LED device 10, blocks such as the first wire-bonding region 21, the second wire-bonding region 22, the third wire-bonding region 23 and the die-bonding region 24 are spaced apart from one another at a specific distance to avoid electrical conductivity therebetween.
Thus, in terms of the configuration of the upper surface of the substrate 20, the blue chip 31, the green chip 32 and the red chip 33 included in the three LED chips 30 are sequentially disposed on the upper portion, the lower portion and the central portion of the die-bonding region 24, the blue chip 31 on the upper portion can be electrically connected to the first wire-bonding region 21 and the second wire-bonding region 22 respectively via two first metal conductive wires 41, the green chip 32 on the lower portion can be electrically connected to the first wire-bonding region 21 and the third wire-bonding region 23 respectively via two second metal conductive wires 42, and the red chip 33 on the central portion can be electrically connected to the first wire-bonding region 21 via a single third metal conductive wire 43 since the adopted blue chip 31 and the green chip 32 are horizontal LED chips while the adopted red chip 33 is a vertical LED chip. Thereby, operations of the blue chip 31, the green chip 32 and the red chip 33 can be controlled according to signals inputted from an external controller.
However, in the aforesaid circuit design in which the upper surface of the substrate 20 is provided with three wire-bonding regions (i.e., the first wire-bonding region 21, the second wire-bonding region 22, and the third wire-bonding region 23) and one die-bonding region (i.e., the die-bonding region 24), limitations are made to the minimum area of each of the wire-bonding regions and the die-bonding region and specific distances need to be kept between each blocks to avoid electrical conductivity therebetween. Therefore, the size of the substrate 20 is restricted to not be smaller than a specific size. In other words, such information signage boards adopting the LEDs cannot meet the requirements of improving the resolution or to decreasing the size of the finished product due to the size limitation.
Accordingly, a long-felt need in the art is to provide an LED device, of which the substrate is with circuit design that requires a smaller substrate area so as to improve the resolution as well as to decrease the size of the product.